MacCoun, R. J., & Kerr, N. L. (1988). Asymmetric influence
in mock jury deliberation: Jurors’ bias for leniency.
Journal of Personality and Social Psychology, 54,21–33.LINEUPFILLERSELECTION
Lineup fillers prevent unreliable witnesses from
guessing the identity of the police suspect and should
allow for a fair recognition test for those witnesses
who do remember the culprit. The primary strategies
for selecting fillers for criminal identification lineups
are presented in this entry. The suspect-matched and
perpetrator-description-matched strategies are two
methods of constructing lineups that have been com-
pared by researchers. Additionally, care should be
taken to ensure that the structure of the lineup is uni-
form across members. To assess the fairness of a
lineup, several indices that measure lineup bias and
lineup size have been developed.The Function of Lineup Fillers
Lineup fillers, also known as foils (an innocent person
in a police lineup), serve the major purpose of testing
an eyewitness’s recognition memory for a criminal
perpetrator so as to establish evidence that the suspect
is guilty of the crime. Fillers also serve to screen out
unreliable witnesses: Witnesses who identify foils may
have a weak memory for the perpetrator or may be
guessing. With respect to the problem of guessing, the
probability that a witness will select the suspect from a
lineup based on chance alone equals 1/k, where k
equals the number of foils in the lineup. Having more
options during the identification test decreases the
probability that witnesses will identify the suspect by
guessing alone. Additionally, presenting foils that
resemble the suspect works toward preventing the wit-
ness from being able to deduce who the suspect is sim-
ply by eliminating improbable choices from the lineup.Filler Selection Strategies
There are two primary filler selection strategies that
have been investigated by researchers. First, foils may
be selected for the lineup on the basis of their similarity
to the physical appearance of the suspect, a procedure
that is known as the suspect-matchedstrategy. Second,
foils may be selected based on their resemblance to aphysical description of the perpetrator given by the eye-
witness, a procedure that is termed the perpetrator-
description-matchedstrategy.
Two main concerns arise when foils are selected for
the lineup on the basis of the suspect-matched strategy.
First, if the suspect is not the culprit and is in fact inno-
cent, then selecting the foils based on their match to the
innocent suspect may result in a lineup in which the
similarity of the foils to the perpetrator is low. This is a
concern in cases in which the suspect is apprehended
because he or she is physically similar to the descrip-
tion of the culprit given by an eyewitness. In such cases,
the suspect may be the only one in the lineup that
resembles the perpetrator. As a result, the innocent sus-
pect might be frequently identified from lineups in
which the foils are chosen on the basis of their match to
the innocent suspect’s appearance, a consequence that
is known as the backfire effect.Another concern that
arises when the foils are chosen for the lineup using the
suspect-matched strategy is that if the suspect is in fact
the culprit, then the foils could potentially be too simi-
lar to the suspect, and thereby decrease the odds that a
witness who remembers the perpetrator can distinguish
the guilty suspect from the foils.
In view of these concerns, the perpetrator-description-
matched strategy has been proposed. In the event that
an innocent suspect is in the lineup, the perpetrator-
description-matched strategy is thought to ensure that
the innocent suspect and the foils have the same proba-
bility of being chosen. The rationale is that if investiga-
tors select the foils and the suspect for the lineup using
the same criteria (i.e., their match to the witness’s
description), then the foils should look no more
like the perpetrator than does the innocent suspect.
Additionally, for a witness who remembers the perpe-
trator, the perpetrator-description-matched strategy
allows for propitious heterogeneity, a term that refers to
having sufficient variability across lineup members to
allow the witness to recognize a guilty suspect.
Some researchers studying lineup identification
in the laboratory employ a hybrid of the suspect-
matched and perpetrator-description-matched strate-
gies. A pool of potential foils that fit the modal
description of the target (i.e., the “perpetrator”) is
obtained. Participant raters then judge the similarity
of each face in the pool to the target. The faces that are
rated as being the most similar to the target are
selected as fillers. An additional method on the hori-
zon for the selection of fillers for lineups is the use of
principal components analysis (PCA). PCA representsLineup Filler Selection——— 455L-Cutler (Encyc)-45463.qxd 11/18/2007 12:43 PM Page 455